The Viper was small, fast, and in your face

On the other hand, General Dynamics system analyst Pierre Sprey “was a true Luddite, opposed to any advanced technology,” says Loh. “His agenda was to produce the cheapest fighter for daytime air combat in Europe against Warsaw Pact forces.”

Loh remembers that Pentagon analyst Tom Christie also wanted to validate the energy maneuverability theory, but was more interested in building an affordable fighter to augment the F-15. Loh, the pragmatist, tried to balance the competing personalities so they could actually build a lightweight fighter: “I had to try to channel the agendas away from features that would make the LWF unacceptable to Air Force leadership,” he says.

Despite the differences, Loh says, “All of us…were concerned about the cost trend in fighters…where each generation of fighter was going to be 10 times more expensive than the previous generation.”

Although the Lightweight Fighter program is often portrayed as an end-run by a highly principled officer (Boyd) around the unwieldy military acquisition system, retired Lieutenant General Glenn Kent points out in his 2008 memoir, Thinking About America’s Defense, that “the reality…was more nuanced.” With the F-15 alone, the Air Force would not have been able to build the number of airplanes needed in Europe to overcome Warsaw Pact forces. According to Kent, because an all-F-15 force was too expensive, the Air Force finally agreed to look at the LWF primarily as the “low” part of an affordable “high-low” mix of weapons systems.

At the time, Secretary of Defense James R. Schlesinger, an advocate of prototyping programs, approved an Air Force proposal to build two Lightweight Fighter prototypes. At first, although Air Force leaders were willing to let the prototypes fly, they had no plans for production. The F-15 was the only child they wanted.

However, Loh says, “I knew all along the LWF was going to interfere with the F-15.”

Air Force Systems Command test pilots and Tactical Air Command pilots flew the YF-16 and YF-17. By all accounts, the -16’s performance was phenomenal, but the aircraft had inherited a major problem from the F-15: the F100 engine. Installed on the F-16, it had an alarming habit of refusing to provide more than idle thrust at the worst possible moments. On their first flights, Ettinger and retired Colonel Dean Stickell both experienced engine “rollbacks”; Ettinger didn’t even make it out of the chocks, but Stickell’s rollback occurred shortly after takeoff. Fortunately, he was at 15,000 feet and right over the runway at Edwards. The engine was also prone to compressor stalls, a phenomenon that can produce spectacular flames out both ends of the engine, with explosions violent enough to knock a pilot’s feet off the rudder pedals. Until the engine problem was fixed, the YF-16 had to stay within deadstick landing distance of the base.

Eventually, both the YF-16 and YF-17 passed their tests. At least in part because of NATO interest in the airplane, Schlesinger persuaded the Air Force to buy the Lightweight Fighter “winner.” In return, he would let the Air Force buy all the F-15s it had originally wanted and would increase the number of Air Force wings, with the caveat that the new wings be equipped with LWFs.

In agility, acceleration, and turn rate, the YF-16 dominated the YF-17 above transonic speeds. In addition, the single-engine YF-16 also had a huge advantage in fuel consumption, and the airplane afforded the pilot increased G-tolerance and better visibility. Still, the newcomer had no mission of its own. The Air Force might assign it to supplement its fighters—the F-15 and F-4—or its ground attackers—the F-111 and A-10—in their primary roles.

In June 1972, the Air Force had sent Loh to the Massachusetts Institute of Technology for a master’s degree in aeronautical engineering and assigned him to the prototype office at Wright-Patterson Air Force Base in Ohio to manage the budget, contracts, and overall engineering for the Lightweight Fighter. When the F-16 was selected, the Air Force formed a system program office at Wright-Patterson, where Loh signed on as director of projects, with the responsibility to integrate the avionics and weapons systems on the airplane. But he was in a quandary. Air Force four-star generals had ordered him not to put a Sparrow missile on the F-16 because they didn’t want it competing directly with the F-15. But they didn’t say anything about inventing a new missile.